Answer:
(y - 8x) (y + 7x)
Explanation:
This person's videos helped me out so much with questions like these.
Brian McLogan -
1) Factoring an expression with a greater than one and two square variables 8x^2 -6xy -9y^2
2) Learn How to Factor a Trinomial in Your Head When a is not Equal to One
I'm not paid to do this, I genuinely recommend you watch these two videos, because it helped me tremendously when I once did a question like this.
Have a blessed day!